Polymer80 80% Lower Receiver and Jig Kit (LR-308)

For builders seeking a precision platform in the large-frame AR category, the Polymer80 80% Lower Receiver and Jig Kit (LR-308) represents a critical component for a custom .308 Winchester or 6.5 Creedmoor build. This kit provides the foundation needed to complete a serialized, semi-automatic rifle from an unfinished receiver. Designed specifically for the DPMS LR-308 pattern, this kit allows the builder to mill, drill, and assemble the lower at home using the included jig system. With a focus on repeatability and structural integrity, this kit offers a professional-grade solution for those who demand control over every aspect of their firearm’s architecture.

Overview

The Polymer80 80% Lower Receiver and Jig Kit (LR-308) is a complete package designed to transform a raw 80% blank into a functional lower receiver. The kit includes the unfinished polymer receiver, a dedicated multi-jig system, drill bits, end mill, and all necessary installation hardware. Unlike standard aluminum lowers, the polymer construction reduces overall weight without sacrificing dimensional accuracy. The LR-308 pattern ensures compatibility with a wide range of aftermarket parts, including triggers, buffer tubes, and grip assemblies. This kit is intended for individuals who possess the mechanical aptitude to complete the machining process with standard tools such as a drill press or handheld router.

Features & Specs

The Polymer80 80% Lower Receiver and Jig Kit (LR-308) is engineered for precise material removal and repeatable results. The following features define this build kit:

• Material: High-impact, glass-reinforced polymer designed to withstand the cyclic forces of .308 Winchester and 6.5 Creedmoor cartridges. The receiver is molded to DPMS LR-308 specification with hardened steel trigger pin inserts and a reinforced buffer tower.
• Jig System: Includes a multi-position clamping jig with hardened steel guide bushings. The jig accommodates both drill press and router operation, providing indexed reference points for the fire control pocket, trigger pin holes, and hammer pin holes.
• Hardware Package: Kit contains a 3/8-inch end mill, 1/8-inch drill bit, 5/32-inch drill bit, and all stainless steel roll pins, springs, and detents required for lower receiver completion. The jig also includes a depth stop collar to prevent over-milling.

Additional specifications include a standard AR-15 grip angle compatibility, a threaded buffer tube interface (1-3/16-18 TPI), and a flared magazine well for faster reloads. The receiver is designed to accept standard LR-308 lower parts kits and magazines.

Who It’s For

This Polymer80 80% Lower Receiver and Jig Kit (LR-308) is intended for experienced firearm builders who are comfortable with machining processes and have access to a drill press or router. It is ideal for those who wish to build a large-frame AR without the constraints of a pre-serialized receiver. The kit is suited for precision rifle enthusiasts, competition shooters, and hunters who require a lightweight yet durable lower for a custom long-range build. Builders should have a working understanding of fire control group geometry and the ability to measure tolerances with calipers. This is not a beginner-level project; it requires patience, attention to detail, and adherence to safety protocols during the milling process.

Shipping & FFL

Because this product is an 80% lower receiver that is not yet a firearm, it does not require transfer through a Federal Firearms License (FFL) holder for shipment. The Polymer80 80% Lower Receiver and Jig Kit (LR-308) can be shipped directly to your residence within the United States. However, it is the buyer’s sole responsibility to verify that possession and completion of an 80% receiver are legal under all applicable federal, state, and local laws. Some jurisdictions impose restrictions on the purchase, possession, or machining of unfinished receivers. By purchasing this kit, you confirm that you are legally eligible to own firearms and that your local laws permit the completion of unserialized lower receivers. We strongly recommend consulting with a legal professional before purchase if you are uncertain about your jurisdiction’s regulations.